This invention relates to valves used for the control of liquids or gases and which opening or closing action is dependent on a rotary valve stem motion caused manually or by automatic actuating means. More specifically, my invention relates to so-called ball valves, featuring usually a spherical plug with a cross-bore located between a pair of plastic seal rings and rotable over a 90.degree. quadrant between the open and closed position.
For high pressure service, these highly polished and precision ground balls or spheres have to be supported by journal bearings located externally of the sphere and within the surrounding housing. Such construction, in turn, requires housings made of two separate halves either screwed or welded together. The cost of producing such relatively complicated housings and balls with forged or cast-on bearing stubs is high. The main objective of my invention is therefore to retain a one-piece housing and to eliminate the use of a difficult to machine completely spherical ball plug which, in turn, enables the placement of the required journal bearings inside the housing bore, thereby effecting great cost savings.
Another object of my invention is the provision of an insert type trim arrangement, allowing quick removal of all functional parts from the housing for better servicing and speedy assembly. A type of insert type ball or butterfly valve has been known and is described in U.S. Pat. No. 3,636,972. However, the described construction is featuring a valve assembly inserted within a housing and in the process providing a cavity between said insert and housing bore to enable circulation of a heating or cooling fluid around the inner valve assembly. Furthermore, while U.S. Pat. No. 3,636,972 shows an embodiment (FIG. 6 or FIG. 7) indicating a butterfly valve with an eccentric vane, which shows some remote similarity with my invention, there is no indication of how valve stems 324 or 322 can be removed from the one-piece tubular valve body 312, i.e. the patent indicates an un-workable design. My invention, on the other hand, teaches the use of removable bearing bushings which effectively lock the plug bearing stubs in position, once the valve is assembled, thereby completely eliminating the use of pins, screws or other fastening devices, which could become dislodged during service and thereby greatly impair the reliability of such a valve.
Yet, another object of my invention is the use of a flexible plastic seal, which is fluid pressure actuated and which is backed-up by a stainless steel sealring, which comes into play, in case the plastic seal is destroyed, thereby providing additional fire safety.
Other objects and advantages will be readily apparent from the following detailed description.